Suitable as primary filters and can be installed in PF-1 Frames, K-Trac Framing Modules, Surepleat Side Access Housings and similar existing hardware. They may be used as prefilters for Precision Pak, Super-Flow® V, PrecisionCell and Rigid-Air filters in these frame systems and in Sureseal Side Access Housings.Please contact your preferred service center directly to special order any custom sizes